According to cosmological theory, the expanding universe has no preferred direction. Thus, the cosmos may be likened to a rising loaf of raisin bread, with the raisins playing the roles of galaxies. Viewed from Earth (or anywhere else), the motion of a distant galaxy should be determined by the overall cosmic expansion. Now, following on their earlier work presented in 2008, Alexander Kashlinsky of NASA’s Goddard Space Flight Center and colleagues report that superimposed on the cosmic expansion is a universal flow along the line from Earth to the Centaurus and Hydra constellations. The “dark flow,” as the authors call it, was revealed in the cosmic microwave background by minuscule temperature fluctuations that arise when x-ray-emitting gas from galaxy clusters scatters off CMB photons. A catalog of more than 1000 x-ray-luminous galaxy clusters told Kashlinsky and company where in the Wilkinson Microwave Anisotropy Probe’s five-year data set they should look for those fluctuations. The researchers had to average over ensembles of clusters to see evidence for the dark flow, which persisted unabated to the furthest measurable reaches, 2.5 billion light-years away. It’s as if—and this is a literal possibility—matter beyond the edge of the visible universe is pulling the entire cosmos toward it. (A. Kashlinsky et al., Astrophys. J. Lett. 712, L81, 2010.) —Steven K. Blau
An unexpected cosmic current
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I guess if you go by the horizon theory where it states that light hasn't had enough time to reach us from beyond the boundary of the visible universe then you may possibly assume that there's a whole part of the universe which we can't yet see, but it is imposing some influence on our part of the cosmos due to the density of a gravitational attractive super or mega cluster of matter beyond the horizon. Could be true...
This is unbelievable. it is said that the expanding universe has no preferred direction. Is everything random. lately I've started believing it.
Has the following explanation for the large scale structure of the universe been considered and discounted?
Consider a universe many billions of times the size of the observable universe, so big that the homogeneous nature of the universe could even be a false illusion.
At a very large distance away, the events of the "big bang" could be still taking place, resulting in a universe which is continually being renewed, with matter and energy there undergoing continuous inflation.
This continual inflation energy would force the observable universe to move away rapidly, and also if the observable universe is relatively small, the expansion away from us might appear similar in all directions, as we observe.
If this scenario has been going on for some time, there may also be gravitational acceleration towards a large amount of matter that is already out there.
Can the above explanation be discounted with information that we already have? This dark flow paper seems related to this.
On a separate note, some have wondered about an edge to our universe. If black holes are no longer a part of our universe, then perhaps the "edges" to our universe are everywhere?
Just throwing it out there.. Until we get more information there are probable any number of possible explanations that appear to fit, but very fascinating nonetheless.
Very reliable information. Many thanks for this!